Insecurity about my weight?

(a little long, but please read if you want) Well im 15 years old and 6ft.2. i'm soon to be 16 and actually on a diet right now. its been 3 months without junk and lost around 15 pounds. although i have a huge goal to lose 100. i dont look that fat if u see me(my height) but its bad like no joke. in my honest opinion i feel if i lose my weight i can start fresh and be happier. it affected my relationships with girls and friends. i have friends but i try too hard just to figure out who i am. i think thats the reason why i call myself a weird, innocent dude (although im really respectfull and trustworthy, just a fact :P). i just wanna know how i can build self confidence during my diet, yet stop comparing myself with others and lose my weight because i wanna do it for myself. no jokes or other weird answers please, i just want some good advice. Thank you :]